If you don't have a mixer, any suggestions on hand mixing this bread?

You can do it the old fashioned way... with your hands! I actually prefer that to a mixer.

A Danish dough whisk mimics some of the motion of kneading and certainly makes the task easier, especially In first combining ingredients. As the dough becomes stiffer, hands are more effective. Hand kneading was the way our ancestors made bread, long before electric appliances were invented. Given the flour and water ratios in this recipe, hand kneading should work just fine.

I agree a mixer is helpful in making bread but is not necessary. If you add about 1/3 of the total flour and then mix it with a wooden spoon until you see it is becoming a cohesive mass with some elasticity. Then continue adding the flour, beating as you go, until it is too stiff to stir, turn it out and knead it by hand. This is a tried and true method, takes more effort but is totally doable.

Too many typos in my previous answer. Read this version instead. Sorry.

Having a stand alone mixer helps a great deal when making bread, particularly a bread that requires kneading. Any bread can be done by hand but will take way longer to knead. I have done it and I can attest to it being a good exercise for hands and arms. LOL
Step 5 of the recipe where you have to incorporate all the butter and "continue to knead the dough until it pulls away from the sides of the bowl a bit, about 10 minutes" may translate to 20 minutes of doing so by hand. It just requires more patience. You should google and look for the many videos on how to best knead a dough by hand. When I make bread, I like to make sure that the dough passess the windowpane test which entails taking a bit of dough (walnut size or so) and stretching it with hands to see if it stretches into a thin line membrane without breaking. Achieving this test kneading a dough by hand can take patience.

Having a stand alone mixer helps a gread deal when making bread, particular a bread that requires kneading. Any bread can be done by hand but will taker way longer to knead. Step 5 of the recipe where you have to incorporate all the butter and "continue to knead the dough until it pulls away from the sides of the bowl a bit, about 10 minutes" may translate to 20 minutes of doing so by hand. It just requires more patience. You should google and look for the many videos on how to best knead a dough by hand.

hi whitney! i can happily report that i've made this bread a few times without a mixer (it is very, very good). everything can be done with a wooden spoon until the dough gets too thick, around step 3 or 4, after which i've used my hands to knead (and rub the butter into the dough, almost like making biscuits or pie crust). i hope this helps!